What is a BTU?

BTU stands for British Thermal Unit, a measure of energy. One BTU is not much: it's equal to 0.25 food calories or about the amount of energy in the tip of a match. To put this in perspective, the food energy in a peanut butter and jelly sandwich is about 1250 BTU, one kwh of electricity is equivalent to 3,412 BTU, a gallon of gasoline contains about 125,000 BTU, and one short ton of coal (2000 lbs) contains about 20 million BTU.

Because a single BTU is so small, energy is usually measured in thousands or millions of BTU. For entire economies, energy is measured in quadrillion BTU, or "quads" for short. A quadrillion is equal to 10^15. In 2002, total US energy consumption was 97.4 quads.

The metric equivalent of the BTU is the Joule. One quad equals approximately 1.055 Exajoules (10^18 Joules).